In general, electric vehicles (EVs) are continuously being developed as part of efforts to ease environmental problems and develop alternative energy sources. An EV is a vehicle that can be powered by driving an alternating current (AC) or direct current (DC) motor using power of a battery. EVs are classified into battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs). A BEV uses power of a battery to drive a motor, and recharges the battery when the power is consumed. Meanwhile, an HEV generates electricity by the running of an engine to charge a battery, and the generated electricity drives an electric motor, thereby making the vehicle move.
In addition, HEVs are classified into two basic types: series and parallel. In series-type HEVs, mechanical energy output from an engine is converted into electric energy through an electrical generator and the electrical energy is supplied to a battery or a motor. The motor drives the drivetrain, and the engine and the generator are added for increasing mileage compared to that of a conventional EV. Meanwhile, parallel-type HEVs run on the power of battery and/or the engine (gasoline or diesel). The parallel-type HEVs use two power sources and can be driven simultaneously by the engine and the motor according to driving conditions.
Further, an EV is mounted with an electric motor (driving motor) for driving a vehicle and a high voltage battery for supplying power to the electric motor. The battery is a source of energy for driving the electric motor and is capable of supplying power to the electric motor using an inverter. The battery is a secondary battery that can be charged and discharged. The battery may be mounted in the form of a battery pack in an EV, and battery modules including a plurality of cells may be connected in series to obtain necessary power.
The battery mounted in the EV inevitably generates heat during the operations thereof, and thus, a technique for controlling the heat generate may also be required. For example, the battery affected by the generated heat may be cooled using air cooling or water cooling. Water cooling is advantageous in excellent cooling performance, but is disadvantageous in relatively complex configuration, cost, marketability, and the like, and thus, air cooling is more often being utilized instead of water cooling.